• Proceedings of the Korean Institute of Building Construction Conference
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• 2023.05a
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• pp.133-134
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• 2023

In general, all buildings are equipped with various types of handles for opening and closing the door, and unlike wooden doors, steel doors such as fire doors are equipped with a box-shaped door lock box frame surrounding the outside of the door lock to protect the door lock, which is called a cylinder protection cover. These cylinder protection covers have various types and types of fastening structures, and the cylinder protection covers on the market are molded in factories and standardized according to the size and shape of the door lock, requiring various types of cylinder protection covers. Accordingly, a variable cylinder protection cover with a simple prefabricated structure that can fundamentally solve these problems can be used as one cylinder protection cover regardless of the type, shape, and size of the door lock.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2016.05a
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• pp.66-67
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• 2016

Modular construction is attracting attention as the solution of recent problems in construction site. Such as lack of construction workforce, increasing labor costs, work delay due to extreme weather events and strengthening government regulations. However, despite the many advantages, Modular construction has not been activated dueto high construction costs compared to other construction methods. Accordingly, the object of this study is priority derivation of prefabricated house cost reduction factors and use as basic research data. For research performance, we have analyzed the blueprint and bill of quantities of a modular construction based public dormitory which was built in 2013. In result, the proportion of modular construction and on-site construction is 66% and 34%, and the construction cost proportion by activity was devided in to construction(79%), machinery(7%), electricity(5%) and civil(9%). Among these results in order to reduce costs, interior finishing(19.4) steel-frame(16.9%), metal works(13.5%), RC(11.8%), joinery(7.3%) is the order requires focused management.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2020.06a
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• pp.222-223
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• 2020

Recently, as the era of economic cooperation on the Korean Peninsula approaches, the role of the building sector, such as humanitarian reorganization of North Korean housing, is increasing. The purpose of this study is to find out the current location of North Korean housing standards through the North Korean Housing Survey. For the survey, a survey was conducted through 79 North Korean defectors. The main construction methods of North Korean housing are reinforced concrete, steel framed, wooden framed, masonry, and reinforced concrete walled and prefabricated. The residential environment satisfaction items consist of durability, waterproof, heating, ventilation, heat insulation, air tightness, mining, soundproofing, disaster safety, fire safety, and crime prevention. The result is as follows. The housing construction method in North Korea, which lived at that time, consisted of 21 people (30.88%) of reinforced concrete frames, 18 people (26.47%) of wooden frames, 17 people (25%) of masonry walls, 5 people of prefabricated structures (7.35%), and reinforced concrete. Two people (2.94%) were walled. Among these, the wooden frame type had the lowest satisfaction level for each item, and the reinforced concrete had a high level of dissatisfaction in the items of heating, confidentiality, and disaster safety, and the other item had a high level of satisfaction. The masonry wall type has a relatively high satisfaction level in terms of insulation, confidentiality, mining, and disaster safety.

• Steel and Composite Structures
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• v.25 no.2
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• pp.245-255
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• 2017

The performance of an Industrialised Building System (IBS) consists of prefabricated reinforced concrete components, is greatly affected by the behaviour of the connection between beam and columns. The structural characteristics parameters of a beam-to-column connection like rotational stiffness, strength and ductility can be explained by load-rotation relationship of a full scale H-subframe under gravitational load. Furthermore, the connection's degree of rigidity directly influences the behaviour of the whole frame. In this research, rotational behaviour of a patented innovative beam-to-column connection with unique benefits like easy installation, no wet work, no welding work at assembly site, using a hybrid behaviour of steel and concrete, easy replacement ability, and compatibility with architecture was investigated. The proposed IBS beam-to-column connection includes precast concrete components with embedded steel end connectors. Two full-scale H-subframes constructed with a new IBS and conventional cast in-situ reinforced concrete system beam-to-column connections were tested under incremental static loading. In this paper, load-rotation relationship and ratio of the rigidity of IBS beam-to-column connection are studied and compared with conventional monolithic reinforced concrete connection. It is concluded that this new IBS beam-to-column connection benefits from more rotational ductility than the conventional reinforced concrete connection. Furthermore, the semi-rigid IBS connection rigidity ratio is about 44% of a full rigid connection.

• Journal of the Korean Society of Safety
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• v.13 no.4
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• pp.221-229
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• 1998

This study, with a view point to prevent accidents arising from steel structure, construction process, has taken an approach of reviewing related materials and construction safety guidelines, conducting questionnaire surveys and on field surveys. This study has also analyzed and classified accident cases and disclosed elements concerned with those accidents. A comparative analysis of the disclosed elements against the statutory provisions regarding industrial safety and it showed that strict observance of safety rules of the accident prevention measures in industrial safety standards will result in a decrease in accidents. It is concluded, however, that additional accident prevention measures, as suggested below, should be implemented for performing of more practical and positive accident prevention. 1) Thorough review and preparation at pre-working stage at sites : Such elements of fall preventing facilely as supporting ropes and steel fabrications for safety guard rails should be initially reflected on detailed drawings and shop drawings so that they can be installed in advance at fabricating plants. 2) Sets of steel frame stairs for work platform should be installed or secured with priority and temporary installation of such prefabricated platform as scaffolds should be installed in advance with those platform attached to the frame members on the ground whenever possible before they are lifted. 3) A decrease in the rate of accident by more than 10% on Tuesdays and Thursdays, has been shown from the accident analysis so schedule of construction process should consider possible weekday of high risk of accidents such as Tuesday and Thursday. 4) An array of systemized safety activities should be adopted, such as legal installation of safety facilities based on advance safety management plan, maintenance of safety for machinery and construction equipment, and strict compliance of safety rules by workers.

• Journal of Korean Society of Steel Construction
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• v.21 no.6
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• pp.619-626
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• 2009

The use of thin-walled flexural members has proven to be a practical way to achieve the lowest cost in the construction of prefabricated long-span, low-rise building frames in steel. On the other hand, most of these structures are subjected to corrosion due to environmental exposure, which can reduce their carrying capacity. Corrosion damage is a serious problem for these structures as it causes thickness loss. That is, the class of a section (plastic, compact, non-compact, or slender) may change from one to another due to the loss of thickness of the compression flange and web due to corrosion. In this study, the effects of corrosion on thin-walled members in long-span steel frames were evaluated with regard to the moment-rotation curve, initial stiffness, maximum load capacity, stiffness in the post-maximum capacity, and energy absorption.

• Journal of Korean Society of Steel Construction
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• v.27 no.5
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• pp.471-481
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• 2015

Modular building is a prefabricated construction system for building where factory-produced pre-engineered modular units are delivered to site and assembled as substantial elements of a building. There are two basic kinds of modular structures. One is a load-bearing wall structure designed to transfer the load through longitudinal walls. The other is a frame structure composed of columns and beams. For frame structure, square hollow section is often used as a column member and channel as a beam member in modular unit. Lower and upper modules are fasten with bolts via a pre-installed access hole in the SHS column. However, the access holes can weaken the panel zone that would affect the behavior of beam to column connection. The 5 specimens of beam to column connections with parameters of access hole, column thickness and diaphragm were made and this paper describes the test results.

• Journal of Korean Society of Steel Construction
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• v.23 no.4
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• pp.429-438
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• 2011

In this study, the explicit numerical algorithm was proposed to simulate the stress erection process and ultimate-load analysis of the strarch (stressed arch) system. The strarch system is a unique and innovative structural system and member prestress comprising prefabricated plane truss frames erected through a post-tensioning stress erection procedure. The flexible bottom chord, which has sleeve and gap details, is closed by the reaction force of the prestressing tendon. The prestress imposed on the tendon will enable the strarch system to be erected. This post-tensioning process is called "stress erection process." During this process, plastic rigid-body rotation occurs to the flexible top chord due to the excessive amount of plastic strain, and the structural characteristic is unstable. In this study, the dynamic relaxation method (DRM) was adopted to calculate the nonlinear equilibrium equation of the system, and a displacement-based finite-element-formulated filament beam element was used to simulate the nonlinear behavior of the top chord sections of the strarch system. The section of the filament beam element was composed by the amount of filaments, which can be modeled by various material models. The Ramberg-Osgood and bilinear kinematic elastic plastic material models were formulated for the nonlinear material behaviors of the filaments. The numerical results that were obtained in the present study were compared with the experiment results of the stress erection and with the results of the ultimate-load analysis of the strarch unit frame. The results of the present studies are in good agreement with the previous experiment results, and the explicit DRM enabled the analysis of the post-buckling behaviors of the strarch unit frame.

• Steel and Composite Structures
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• v.29 no.5
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• pp.603-622
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• 2018

Precast concrete structures are erected from individual prefabricated components, which are assembled on-site using different types of connections. In the present design of these structures, beam-to-column connections are assumed pin jointed. Bolted billet beam to-column connections have been used in the precast concrete industry for many years. They have many advantages over other jointing methods in component production, quality control, transportation and assembly. However, there is currently limited information concerning their detailed structural behaviour under vertical loadings. The experimental work has involved the determination of moment-relative rotation relationships for semi-rigid precast concrete connections in full-scale connection tests. The study reported in this paper was undertaken to clarify the behaviour of such connections under symmetrical vertical loadings. A series of full-scale tests was performed on sample column for which the column geometry and bolt arrangements conformed to successful commercial practice. Proprietary hollow core floor slabs were tied to the beams by 2T25 tensile reinforcing bars, which also provide the in-plane continuity across the connections. The contribution of the floor strength and stiffness to the flexural capacity of the joint is currently neglected in the design process for precast concrete frames. The flexural strength of the connections in the double-sided tests was at least 0.93 times the predicted moment of resistance of the composite beam and slab. The secant stiffness of the connections ranged from 0.94 to 1.94 times the flexural stiffness of the attached beam. In general, the double-sided connections were found to be more suited to a semi-rigid design approach than the single sided ones. The behaviour of double sided bolted billet connection test results are presented in this paper. The behaviour of single sided bolted billet connection test results is the subject of another paper.